Subtracting decimals
Topic Notes
In this lesson, we will learn:
- How to subtract decimal numbers using base ten (block) models
- That subtracting decimal numbers is the same as subtracting whole numbers, which involves lining up the right place values and exchanging
Notes:
- To subtract decimals with base ten (block) models:
- Remember the three types of blocks used to represent the ones, tenths, and hundredths place values
- "One whole" or hundred block = ones place value
- Column (stick or rod) = tenths place value
- Single square = hundredths place value
![Adding Decimals](
https://dmn92m25mtw4z.cloudfront.net/img_set/math4-2-6-x-1/v1/math4-2-6-x-1-569w.png)
- A subtraction statement is made of: minuend - subtrahend = difference
- Cross out the blocks that you are subtracting (subtrahend from the minuend), until you've crossed out all matching pairs (subtrahend all crossed out).
- Exchange (or "borrow") from a bigger block if you don't have enough blocks to cross out. One big block can be split into 10 of the next smaller type of block (next place value).
![Adding Decimals](https://dmn92m25mtw4z.cloudfront.net/img_set/math4-2-7-x-1/v1/math4-2-7-x-1-701w.png)
- To subtract decimals, line up the decimal point to make sure you are adding the right place values in the same columns. Exchange (borrow) whenever necessary.
- Sometimes, you will have to write one or more extra zeroes to a number after the decimal point (trailing zeroes) when the minuend/subtrahend don't have the same number of place values.